This invention relates to the recovery or removal of uranium by the utilization of Dotory (acorn).
Various chemical forms of uranium compound exist in the waste generated from uranium processing; such as, AUC [(NH4)4 U02 (C03)3], ADU [(NH4)2 U207], uranyl nitrate [U02 (N03)2], etc.
A safe waste treatment should be achieved for the conservation of our ecological system and for national health and environment preservation.
In many countries including Korea, the waste generated from a U02 powder manufacturing process has been treated through a storage treatment method in a lagoon (or pond). However, this method is not sufficient to solve the serious problem of .alpha.-waste treatment. Besides, it is an international tendency to assume more and more severe restrictions and thus each country has been carrying out a research for a new technology.
In case of the U.S.A., an ion exchange method, reverse osmosis method, neutralization and precipitation method, etc. have been developed under the direction of the Department of Energy (DOE).
The Oakridge Y-12 plant had treated the waste in an unlined percolation pond, as in Korea, but starting from 1976 they carried out a research for a substitute process to treat the waste under storage in the pond by use of neutralization, precipitation, anaerobic denitration, coagulation and filtration methods, etc.
Oak-Ridge Nuclear Laboratory (ORNL) performed research to develop many kinds of solid sorbents for the treatment of uranium and DBP in TBP (30%) solvent, but no satisfactory result was obtained.
Under the direction of NRC (Nuclear Regulation Committee) in U.S.A., Sherwood D.R. et al of PNI (Pacific National Institute) reported in 1983 that Ca(OH).sub.2 or lime is most effective to treat the waste of a uranium-containing solution based on the estimation standard for uranium treatment; that is, (1) the quality of water after treatment, (2) sludge handling efficiency and hydraulic quality, and (3) neutralizer cost and acid neutralization efficiency.
Pulley H. et al of DOE have a patent for a coagulation method using calcium fluoride for the removal of uranium from aqueous HF solution.
Herald W. R. et al of Mound Laboratory reported in an analysis of organic and inorganic adsorbents using porous ion exchange resin for the removal of uranium and plutonium for ERDA in 1977 that the hydroxypatite is most effetive one, but the adsorptive resins of physical adsorption are not good for uranium treatment.
In 1983 Crossley, T. J. et al of Westinghouse Electric Corporation got a patent on a uranium treatment method from molybdenum solution, in which HCl acid is used to remove CO2 gas followed by an addition of NH4OH to make the solution alkaline and then uranium is precipitated and filtered.
Crossley, T. J. of Wyoming Mineral Corp has a patent for a uranium treatment method from slurries containing molybdenum, where uranium precipitates in the form of calcium carbonate and calcium uranate by adding alkali metal hydroxide.
In Japan, Mitsubishi Co. obtained a patent in 1981 for a treatment method of uranium oxide (fine particle) which is adsorbed from the waste by iron salt.
Kanebo K.K. et al have a patent of a treatment method using an adsorbent made of titanium compound incorporated into porous media for the recovery of uranium from sea water and General Electric Co., of U.S.A. has a patent for a treatment method of uranium containing waste in U.S.A. (1982) and in Japan (1983).
Mitsubishi Metal Co. holds a patent for a uranium treatment from waste in 1982 and Yoshiwara Tsuneichi et al in Metal Industries got a patent for a uranium removal technology from aqueous ammonium carbonate solution (1978).
Mouton et al of Campanie Generale des Matieres Nuclaires S.A. of France have a patent for a uranium and titanium treatment method from uraniferous and bicarbonate solution by the addition of aluminium salt (1984).
Muzzarelli R. A. of Ancona University in Italy performed research on uranium treatment from sea water or waste by use of derivatives of chitosan and ascorbic acid in 1985 and Fresenius W. et al of Taunusstein of west Germany carried out research to treat a small amount of uranium from water and waste in 1984.
Wu, Quing Chang et al of China investigated uranium treatment with ion exchange resin in 1984 and Galun M. et al of Tel Aviv University in Israel researched uranium treatment from solution by fungal biomass in 1984. Weir, Donald, and Robert et al of Sherritt Gordon Mines Ltd. In South Africa patented a uranium treatment technology from a sulfate solution containing molybdenum in 1983.
Also, Czechoslovakia and Fumania obtained patents on the uranium treatment in 1980 and 1982, respectively, and Skrylev L. D. et al of U.S.S.R. did their own research on the uranium treatment from a dilute solution by flotation in 1980.
In Korea, Chang, In Soon et al of the Korea Advanced Energy Research Institute (KAERI) have a patent on the uranium treatment method by controlling temperature and pH in 1984.
Likewise, a more safe treatment method is required since the amount of radioactive waste is ever-growing due to the increase of U02 production and moreover this treatment of uranium containing waste from nuclear power plants and the uranium recovery are to be carried out in national aspects.